Machine tools, particularly electrically driven hand-held power tools, are principally known in the design of compass saws having a saw blade, driven to reciprocate, as working tool in various configurations and stages of development, including with regard to auxiliary devices that are intended to facilitate working with the machine tool for the user, particularly guiding it along a prescribed working line.
Thus, there are known from practice hand-guided machine tools, inter alia in the form of compass saws, circular saws, hand-held planes or routing machines having mechanical guiding devices, in the case of which the guiding is performed along a reference edge by means of a guide shoe that is connected to the machine via a cantilever transverse to the working direction.
Also known are machine tools, particularly in the form of electrically operated hand-guided compass saws, for example from DE 10 2006 052 808 A1, in the case of which a workpiece side working line that is respectively to be followed is intended to be followed via a sensor unit, particularly an optical sensor unit in the form of a camera, and in the case of which the user of the machine tool is supported in guiding it along the working line via an evaluation unit on the basis of the workpiece side conditions thus detected. This is so, for example, because the position of the working tool in relation to the working line is displayed to the user, if appropriate with supplementary guide instructions. If the machine is equipped as a compass saw with a saw blade, as working tool, that can rotate about its stroke axis, in the case of such a known solution the working line of the saw blade, which is detected by sensor, is followed by appropriate setting of its rotary position, for which purpose the data detected by sensor are converted with computational aid via an evaluation unit into actuating commands for an actuator rotating the saw blade. All that the user need do in this semiautomatic mode is to apply the feed forces for the compass saw, and thus to support the compass saw in a fashion coarsely aligned with the respective working line.
Irrespective of whether only guide instructions are generated for the user on the basis of the data detected by sensor, or whether the compass saw is operated semiautomatically, in view of the relatively high feed rates with compass saws, the user requires information at an early stage so that—in the event of deviations from the desired working line, of the lack of such instructions or of the semiautomatic guidance, for example because of difficulties in detecting a working line, or the absence of a working line—he can intervene in good time if the machine is not switched off automatically.